When Does A Tree Go From Decorative To Dangerous?

Let's face it. When we call someplace a tree-lined street in a leafy suburb, the implication is not that its residents live among deadly hazards. The intent is generally flattering. We like trees - you know, radio shows are hosted by fools like me, but only God can make a tree - except when 70-mile-per-hour winds blow through your neighborhood, as they did in many neighborhoods around Washington, D.C. last Friday.

Trees fell and struck power lines, leaving some areas still blacked out almost a week later and some trees fell on homes, which raises this question, a question that is both aesthetic and economic and one that can divide households. When is a tree near your house more dangerous than decorative? When do you cut it down?

Well, Tchukki Andersen, staff arborist with the Tree Care Industry Association, is in Londonderry, New Hampshire, and we're going to ask her. Welcome to the program.

TCHUKKI ANDERSEN: Oh, thanks, Robert. Nice to be here with you today.

SIEGEL: And, first, is there any standard answer to the question, when is a tree that's close to your house too close to your house?

ANDERSEN: First of all, it depends. It depends on the size of the tree and the type of tree, but more likely, if it's overhanging your house, it's probably too close to your house when, say, the house or the structure is within probably 15 feet of the trunk.

SIEGEL: You said it depends on what the tree is. Are there some trees that are more dangerous near your house or near a power line, for that matter, than other trees?

ANDERSEN: Pine trees, the conifer type of tree that gets very tall and full of foliage up at the top. We find those trees to be the most likely to break in high winds or under ice and snow loads in storms.

SIEGEL: Are there any particular trees, which - not when they're too close to the house, but when just standing anywhere - stand up to wind a lot better than a pine tree?

ANDERSEN: Yeah, sure. The idea is to try to pick or leave trees on your property that are slower growing and grow to a smaller height, like hophornbean trees, ironwood trees or holly trees, trees of smaller stature. Again, I'm getting back to trees that tend to grow slowly so that they grow strong and they have a tendency to put out a larger root area will often be more successful in riding out a high wind storm event.

SIEGEL: After a storm, when you see downed trees, which is more likely the reaction? If we'd just done our homework a bit better, we could have taken down that tree before it took down a power line or before it hit a building or it's luck of the draw. You can't figure out which tree is going to go down in a heavy wind.

ANDERSEN: It'd be great to say, oh, I'm going to step on your property as a trained arborist and I'm going to point to every single tree that's going to experience hazards or broken branches or problems when this storm comes through. But, more likely, if the wind event is strong enough, it doesn't matter the condition of your tree. It could be the healthiest tree on the block and, if there's a strong enough wind or a damaging enough ice storm, everything will go in its path.

SIEGEL: Well, Tchukki Andersen, thank you very much for talking with us.

ANDERSEN: And thank you, Robert. It was my pleasure to talk with you today.

SIEGEL: Tchukki Andersen is staff arborist with the Tree Care Industry Association. She spoke to us from Londonderry, New Hampshire. Transcript provided by NPR, Copyright NPR.